GAMOS/GEANT4 simulation and comparison study of X-ray narrow-spectrum series at the national Secondary Standard Dosimetry Laboratory of Morocco
Introduction
Calibration is a very important service. It is provided mostly by national or international standard dosimetry laboratories. Most developed countries have one or more laboratories for calibration services covering multiple applications of ionization radiation for different levels: radiation protection, radiology, and radiotherapy. The Secondary Standard Dosimetry Laboratory (SSDL) at National Center of Radiation Protection (CNRP), Ministry of Health is the national SSDL in Morocco which is a member of the IAEA/WHO Network of SSDLs.
At the beginning of 2019, the radiation quality of X-ray narrow-spectrum series N-40 to N-300 was established for a new X-ray irradiator (model X80-320-kV-A, Hopewell Designs Inc.) in purpose of defining the radiation protection level (Al-Tuweity et al., 2020). All experimental results for the first 1st and second 2nd half-value layer (HVL) were within 5% of ISO standard 4037–1:1996 recommendation (International Organization for Standardization, 1996 (see Table 1).
The Monte Carlo (MC) method is a very common method to simulate X-ray tubes and radiation transportation. Geant4 code is an MC code. Its areas of application include high-energy, nuclear, and accelerator physics, as well as medical and space science studies (http://geant4.web.cern.ch).
GAMOS is also an MC code based on Geant4 used mainly for radiation protection and medical applications. GAMOS is easy to use and flexible. The comprehensive scripting language makes it easy to implement the most common requirements of a medical physics application without need for C++ coding (Arce et al., 2008), (Arce et al., 2014).
Institute of Physics and Engineering in Medicine report number 78 (IPEM 78) (Cranley et al., 1977) provides a theoretical method developed by (Birch and Marshall, 1979) for calculating X-ray spectra that gives results in close agreement with experimental spectra. IPEM 78 provides illustrations of agreement with experimental data (Cranley et al., 1977). In this work, the generated x-ray spectrums for 40–150 kev were used as .lis file within GAMOS's Input text file. IPEM 78 spectrum is shown in Fig. 1 for six energies between 40 and 150 kV and a tungsten anode with an inclination of 20°.
Section snippets
Experimental
A model of X80-320-kV-A X-ray Irradiator (Hopewell Designs Inc.) was used for the experimental measurements. In purpose to determination of the X-ray beam characteristics, determine the inherent filteration and adjust the fixed filter for the Irradiator system . All experimental details were described in the references (Al-Tuweity et al., 2020) and ISO 4037-1:1996.
SSDL set-up were implemented according to the international specification requirements for an X-ray Irradiator in the Secondary
Results and Discussion
GAMOS results for 1stHVL showed good agreement with experimental and ISO values (see Table 2). For the expermintal, the differences were less than 5.23% for N-80 to N-150, and 10.84% for N-40, while for ISO, the values were between 1.27% and 10.54%. For 2nd HVL, the agreement was better for N-60 and N-80 with respect to both experimental and ISO values, while N-40, N-100, N-120, and N-150 the differences with respect to the experimental values were 6.59%, 9.69%, 6.67%, and 6.67%, respectively,
Conclusion
X-ray radiation quality for narrow-series of new X-ray Irradiator at National SSDL in Morocco was established and simulated by GAMOS/GEANT4. The simulation method using IPEM 78 spectrum data was a useful way to generate the X-ray spectrum for the energies range 40 to 150 kV. IPEM78 were flexible models use. It is necessary to test anothe X-ray generator models which allow more adjustment for different modelation parameters, such as a wider energies range and filter materials setting, to cover
Authors CRediT contributor taxonomy roles
Conceptualization; EL. C., Y.S., J. AL. Data curation; EL. C., J. AL., Formal analysis; EL. C., J. AL., Funding acquisition; Y.S., EL. C., J. AL., Investigation; EL. C., J. AL., P. A. Methodology; EL. C., J. AL., Project administration; EL. C., J. AL., Resources; Y.S., EL. C., J. AL., I. F., Software, Monte Carlo MC; J. AL., A. M. Supervision; EL. C. Validation; EL. C., J. AL., A. M., P. A. Visualization; EL. C., J. AL., Roles/Writing - original draft; J. AL. Writing - review & editing EL. C.,
Declaration of competing interest
The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Acknowledgments
We express our very great appreciation to Mohammed Tazi, Director of the National Center of Radiation Protection (CNRP), Ministry of Health, Morocco, for his graciousness and facilitation of our research work and encouragement for the accuracy of its completion. We also thank the National Center for Scientific and Technical Research (CNRST) for Moroccan Academic and Research Wide Area Network (MARWAN) high-performance computing service, which made the simulation tasks easier and faster.
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